On the correlation between stacking-fault energy and atomic structures of polytypes

Based on the method outlined by Hirth and Lothe for the calculation of theoretical stacking-fault energies of close-packed structures, a somewhat modified procedure is presented to obtain estimates of theoretical stacking-fault energies of polytypic structures. The stacking-fault energy of a polytype is shown to have a definite correlation with its atomic structure; the atomic structure corresponds to a sequence having the minimum stacking-fault energy. The observed correlation has two important bearings on the works relating to the structure and growth of polytypes: it lends definite support to Jagodzinski's layer-transposition mechanism for the growth of polytypic crystals, and it greatly simplifies the calculation of atomic structures of the polytypes.